5—Br—PADAP 高灵敏分光光度法测定食品中微量锌的研究

Highly Sensitive Spectrophotometric Determination of Trace Zinc in Food with 2-(5-Bromo-2-pyridylazo)-5-diethylaminophenol

在 pH8.5硼砂介质中和 TritonX—100存在下,锌与5—Br—PADAP 生成红色三元配合物,其最大吸收峰为555nm,表观摩尔吸光系数(ε)为1.3×10~5L·mol^(-1)·cm^(-1),锌含量在0～12üg/25ml 呈比耳定律。以柠檬酸盐和铜试剂为掩蔽剂,对锌有高灵敏和高选择性。经对猪肝、小麦粉、桃叶三种标准物质和多种食品的测试,均获得满意结果。

A method based on the zinc and 2-(5-bromo-2- pyridylazo)-5-diethylaminophenoi(5-Br-PADAP)form a red ternary Complex at Na_2B_4O_7-HC medium of pH8.0～ 10.7 and presence of Tritonx-100.Its apparent molar ab- sorptivityis 1.31×10~5L·mol^(-1)·cm^(-1) at 555 nm.Beer's Law is oheyed within the concentration range of zinc 0～12/μg/ 25ml.The method is highly sensitive and selective by ammo- nium citrate and sodium diethyldithiocarbamate(Copper reagent)as masking agents.The proposed method has been ap- plied to the determination of zinc in the porkliver,wheat pow- der,peach leaf 3 standard reference material and varied food with satisfactory results.